In general, an engine equipped on a construction machine, etc. is elastically supported via an anti-vibration device having a rubber-like elastic body to suppress the vibration generated by the engine itself and the vibration of the engine caused by the vibration of a vehicular body while travelling on a rough surface and drilling operation.
An anti-vibration apparatus is commonly configured to combine a pair of anti-vibration devices for vertically supporting the engine, and a pair of anti-vibration devices for obliquely supporting the engine, thereby supporting the engine at 4 points. The anti-vibration apparatus is configured such that the anti-vibration device for vertical support elastically supports the engine, which is a vibrating heavy object, effectively in the vertical direction, and the anti-vibration device for oblique support bears horizontal forces associated with the vibration of the engine, in addition to vertical forces.
However, the anti-vibration device for vertical support cannot sufficiently bear horizontal forces, and therefore, as the result of the engine as a whole vibrating in a direction to horizontally pivot around the position of the anti-vibration device for oblique support, the anti-vibration device for vertical support is significantly displaced in the shear direction (horizontal direction). The displacement in the shear direction of the anti-vibration device for vertical support is likely to cause a crack in the rubber-like elastic body, and to prevent such a crack thereby improving durability, the anti-vibration device for vertical support needs to be increased in size.
With regard to this, as shown in FIG. 17, Patent Literature 1 discloses an anti-vibration apparatus whereby an engine 104 is supported by a pair of anti-vibration devices for vertical support 101 and two pairs of anti-vibration devices for oblique support 102, 103, and further, the anti-vibration device for vertical support 101 is disposed near the center of gravity of the engine 104. The anti-vibration apparatus of Patent Literature 1 can prevent the anti-vibration device for vertical support 101 from being significantly deformed in the shear direction even if the engine 104 vibrates in the direction to horizontally pivot around the center of gravity thereof.